[Jarkko]

You can assassinate indy commanders, and then move in a single commander to take over the province. Notice that indies usually have 2-3 commanders per province. Not really a viable strategy as such, but for example EA Abysia might use it to take control of some hard to come by indy province (at the end of a dead end, or an isolated indy province behind another nation) and to get some experience for the flying assassins.

It's also possible to seduce indy commanders. I used this in a game as Patala to gain two bloodhenge druids (and thus nicely got into blood without having to go through the scouts "hunt slaves, empower somebody" -route). There was a third druid present too, but he refused to become seduced (so it resulted in assassination battle). Eventually a single markata scout conquered the province, all those dark vines and whatnots just routed in front of the godly power of markata (or perhaps because they had no commanders left).